1. Field of the Invention
The present invention generally relates to a disk cartridge in which a disk-like recording medium such as an optical disk, a magneto-optical disk and a magnetic disk is accommodated within a cartridge housing so as to become freely rotatable. More particularly, this invention relates to a disk cartridge in which a shutter mechanism capable of opening an opening portion of a cartridge housing to expose a part of a disk-like recording medium includes a first shutter member and a second shutter member.
2. Description of the Related Art
As a disk cartridge in which a disk-like recording medium capable of recording and/or reproducing information such as audio data, video data or data of computers is accommodated within a cartridge housing so as to become freely rotatable, there has hitherto been known a disk cartridge having an arrangement shown in FIG. 1, for example. A disk cartridge, generally depicted by reference numeral 1 in FIG. 1, is a disk cartridge which houses therein a write once read many magneto-optical disk 4 on which users can record and write information such as data of computers later on. FIG. 1 is a schematic perspective view showing an outward appearance of the disk cartridge 1.
Specifically, as shown in FIG. 1, this disk cartridge 1 includes a cartridge housing 2 comprised of a pair of an upper shell 2a and a lower shell 2b, a magnetooptical disk 4 rotatably accommodated within a disk compartment 3 of this cartridge housing 2, or the like. An opening portion 5 which extends from the center portion to one side is formed on both of the upper and lower surfaces of the cartridge housing 2. This opening portion 5 can be opened and closed by a shutter member 6 which can slide along one side of the cartridge housing 2. A presser member 6a is used to protect a tip end portion of the shutter member 6 from being disengaged out of both upper and lower surfaces of the cartridge housing 2.
A disk-like center hub 7 made of a metal is provided at the center portion of the magneto-optical disk 4. The center hub 7 is opposed to the inner end portion of the opening portion 5. Although not shown, a turntable provided on the body of the information recording and reproducing apparatus is mounted on the center hub 7. When the magneto-optical disk 4 is chucked to the turntable, the magneto-optical disk 4 can be rotated at a predetermined velocity (e.g., constant linear velocity). In this case, an information signal is recorded on or reproduced from the magneto-optical disk 4 by a magneto-optical pickup device the head portion of which is inserted into the opening portion 5.
However, a conventional disk cartridge having the above arrangement, the shutter member 6 which opens and closes the opening portion 5 is formed as substantially a U-shape in cross section. This shutter member 6 is fitted into one side of the cartridge housing 2 and the shutter member 6 slides along the above one side of the cartridge housing 2 to open and close the opening portion 5. As a consequence, a large space is produced between the cartridge housing 2 and the shutter member 6 so that very small dusts or the like cannot be prevented from entering into the disk cartridge 2 from the above large space.
In the current in which optical disks are increasing their storage capacities and are increasing their recording densities in recent years, the pitches of the recording patterns are becoming narrower and the linear density is increasing. When read or write beams are interrupted on the recording surface smudged by dusts or the like, or the information recording surface is scratched, information cannot be read out from or cannot be written in the optical disk or the magneto-optical disk normally. To solve this problem, in the disk cartridge according to the related art, as shown in FIG. 1, the shutter member 6 having substantially the U-shape cross section is attached to one side of the cartridge housing 2 so as to become slidable. When the shutter member 6 is slid along the above one side of the disk cartridge 2, the opening portion 5 is opened or closed to protect the information recording surface of the optical disk or the like from being smudged or scratched by dusts or the like.
As the optical disk or the magneto-optical disk is increasing its storage capacity more and is also increasing its recording density more, very small dusts which had been negligible become more influential on the optical disk or the magneto-optical disk 4 when information is written in or read out from the optical disk or the magneto-optical disk 4. The above shutter member 6 whose cross-section is substantially the U-shape cannot satisfactorily protect very small dusts or the like from entering into the cartridge housing 2. In this case, when the information recording surface of the magneto-optical disk 4 is smudged by very small dusts or the like entered into the cartridge housing 2, the information recording surface is brought to the state similar to the state in which the information recording surface is smudged and scratched by dusts or the like with the result that information cannot be normally read out or written in the information recording surface of the magneto-optical disk 4.
In view of the above aspect, the assignee of the present application has previously proposed a patent application concerning a disk cartridge shown in FIG. 2 (see Japanese patent application No. 11-195044). As shown in FIG. 2, a disk cartridge, generally depicted by reference numeral 8, includes a cartridge housing 9 comprised of an upper shell 9a and a lower shell 9b, an optical disk 11 accommodated within a disk compartment 10 of this cartridge housing 9, a shutter mechanism 13 for opening and closing an opening portion 12 which is formed through the cartridge housing 9 so as to expose a part of this optical disk 11, a cover member 14 attached to the cartridge housing 9 so as to protect this shutter mechanism 13, or the like.
The cartridge housing 9 is formed by joining and fastening the upper shell 9a and the lower shell 9b. The optical disk 11 is accommodated within the disk compartment 10 of this cartridge housing 9 so as to become freely rotatable. The cover member 14 is attached to the lower shell 9b of this cartridge housing 9 so as to cover the shutter mechanism 13. This cover member 14 can protect the shutter mechanism 13 and can prevent the cartridge housing 9 from being smudged by dusts or the like.
The shutter mechanism 13 of the disk cartridge 8 is comprised of a first shutter member 15 and a second shutter member 16. The first shutter member 15 is used to open and close the opening portion 12 defined on the cartridge housing 9 at its recording and/or reproducing opening portion into and from which an optical pickup device of a disk recording and reproducing apparatus is inserted and ejected. The first shutter member 15 is comprised of a shutter portion 15a and a belt-like portion 15b. The shutter portion 15a is shaped as substantially a trapezoid in which one oblique side is shaped as a circular arc. The belt-like portion 15b is extended from this circular arc-like oblique side. The belt-like portion 15b includes a circular arc-like guide portion 15bl continued to one side of the circular arc-like oblique side and which has a radius of curvature of approximately the same as that of the circular arc-like oblique side and a rectilinear guide 15b2 continued to the other side of the circular arc-like oblique side and which is protruded from the other side rectilinearly.
This belt-like portion 15b is movably accommodated within a guide portion 17 formed between an inner wall 9al of the upper shell 9a and a peripheral wall 9bl of the lower shell 9b. The guide portion 17 is shaped like a circular arc so as to surround the disk compartment 10. One end of this guide portion 17 is closed by a side wall 9a2 of the lower shell 9b. On the other hand, the other end of the guide portion 17 is opened to a side wall 9a3 of the upper shell 9a and an operating portion 13a provided at the tip end of the rectilinear guide 15b2 is exposed from the opening portion. When the operating portion 13a is pressed and moved within a guide groove 17b defined on the side surface of the cartridge housing 9 and thereby moved on the back side, the first shutter member 15 is changed from the state shown in FIG. 3 to the state shown in FIG. 4. As a result, the shutter portion 15a is rotated and changed to open the recording and/or reproducing opening portion of the opening portion 12.
As the first shutter member 15 is rotated, the second shutter member 16 is rotated in the opposite side of the first shutter member 15. Specifically, the second shutter member 16 is rotatably supported to the cartridge housing 9 by a support pin 16a at one corner portion of the back side of the cartridge housing 9. The other end of the second shutter member 16 is extended up to the center portion of the cartridge housing 9 and is spring-biased to the side of the shutter member 15 under spring force of a coil spring 18, whereby an engagement portion 16b formed at the front end edge of the second shutter member 16 is brought in contact with a convex portion 15c formed at the rear end edge of the first shutter member 15.
The convex portion 15c of the first shutter member 15 is located at substantially the center portion of the front and rear direction of the cartridge housing 9 as shown in FIG. 3 under the condition that the first shutter member 15 closes the opening portion 12. In this state, as shown in FIG. 4, when the first shutter member 15 is rotated to open the opening portion 12, the convex portion 15c is moved to the back side of the cartridge housing 9. As a consequence, movement force of the convex portion 15c acts on the engagement portion 16b and the second shutter member 16 is withdrawn to the back side against the spring force of the coil spring 18. When the second shutter member 16 is rotated, of the opening portion 12, there is opened and closed a drive opening portion into and from which the turntable of the rotary drive mechanism is inserted and ejected.
In the above disk cartridge 8 according to the related art, since the shutter mechanism 13 is comprised of a combination of the two shutter members 15, 16 and the shutter mechanism 13 is protected by the cover member 14, there can be achieved an effect that dusts or the like can be effectively protected from entering the cartridge housing 9.
However, in the first shutter member 15 and the second shutter member 16, the engagement portion 16b is spring-biased and engaged with the convex portion 15c under spring force of the coil spring 18 and the respective end faces of the pair of the shutter members 15, 16 are butted with each other under spring force of the coil spring 18 to thereby close the opening portion 12. As a result, it is unavoidable that a space is produced between the end faces of the butting portions of the first and second shutter members 15 and 16 and that dusts or the like enter into the cartridge housing 9 from the above space.
In view of the aforesaid aspect, it is an object of the present invention to provide a disk cartridge in which butting portions of a pair of shutter members are overlapping with each other when a shutter mechanism is closed so that a coupling portion of the pair of shutter members have a labyrinth function to effectively suppress or prevent dusts or the like from entering the disk cartridge.
According to an aspect of the present invention, there is provided a disk cartridge which is comprised of a cartridge housing formed of a pair of shells so as to form therein a disk compartment, a disk-like recording medium accommodated within the disk compartment so as to become freely rotatable and a shutter mechanism having a pair of shutter members attached to the cartridge housing, the pair of shutter members rotatably coupled to each other and the respective shutter portions being butted to each other to close an opening portion of the cartridge housing when the shutter members are being closed, wherein a butt portion of at least one of the pair of shutter members has a concave portion with which a butt portion of the other shutter member is engaged.
With the above arrangement, in the disk cartridge according to the present invention, when the shutter mechanism is closed, the butt portion of one shutter member overlaps with the butt portion of the other shutter member. As a consequence, the labyrinth function can be demonstrated between the pair of the shutter members, whereby fluid can be made difficult to pass through the butt portions and dusts or the like can be made difficult to enter the cartridge housing.
In the disk cartridge according to the present invention, the butt portion of the one shutter member has a protrusion extended in the direction intersecting a thickness direction of the shutter member and the butt portion of the other shutter member has an oblong hole with which the protrusion is engaged.
With the above arrangement, the protrusion of one shutter member is entered into the oblong hole of the other shutter member and the labyrinth function is demonstrated by a combination of the protrusion and the oblong hole. Therefore, since the opening portions can be more reliably closed by the pair of the shutter members, it is possible to effectively prevent dusts or the like from being entered into the disk cartridge.
In the disk cartridge according to the present invention, the protrusion has a slope surface formed at least at its one surface intersecting its longitudinal direction and the oblong hole has a slope surface having approximately similar inclination at its surface opposing to the slope surface.
With the above arrangement, since the slope surface provided on the oblong hole is opposed to the slope surface provided at least on one surface of the protrusion, a space between the pair of the shutter members can be made constant and a more highly-dustproof property can be maintained.
In the disk cartridge according to the present invention, the length of the longitudinal direction of the oblong hole is longer than the length of the longitudinal direction of the protrusion and a pair of shutter members can be relatively moved in the longitudinal direction.
With the above arrangement, since the length of the protrusion is made longer than that of the oblong hole, dimensional errors and assembly errors of the pair of the shutter members can be absorbed by the protrusion and the oblong hole so that the dustproof property can be improved and dusts or the like can effectively be prevented from entering into the disk cartridge.
In the disk cartridge according to the present invention, the butt portions of the pair of shutter members include protrusions extended in the directions intersecting the thickness direction and an oblong hole with which a protrusion formed on the butt portion of the other shutter member is engaged.
With the above arrangement, since the protrusion and the oblong hole are respectively formed on the butt portions of the pair of the shutter members and the oblong hole and the protrusion are engaged with the oblong hole and the protrusion of the other shutter member, respectively, the space between the pair of shutter members can be made constant and there can be provided the highly-dustproof disk cartridge.
In the disk cartridge according to the present invention, the respective shutter portions of the pair of shutter members are shaped as substantially triangles and long sides of the triangles are butted so as to form the whole of the shutter portion as substantially a rectangle.
With the above arrangement, the relatively large opening portion formed of the wide and long recess can be opened and closed reliably by a combination of the two shutter portions shaped as substantially triangles.
In the disk cartridge according to the present invention, one shutter member of the pair of shutter members is rotatably supported to the disk cartridge, the other shutter member is rotatably supported to one shutter member and includes a belt-like portion the tip end portion of which is protruded to the outside of the cartridge housing and the pair of shutter members can be opened and closed with application of external force to the belt-like portion.
With the above arrangement, the pair of the shutter members can be rotated with application of external force to the tip end portion of the belt-like portion such that they can come close to each other or come away from each other. Accordingly, the opening portion can be opened and closed reliably and smoothly by moving the pair of shutter members close to each other or distant from each other.